Allright, lets start at the top

I drive an a4 2.8Q 30v right?

So I've been fiddling with this check engine light since I bought the car and just when I thought I found the problem, bam! I didnt....

P1138
Definition
Long term fuel trim add. Fuel B2 system too lean
Explanaiton
Failed MAF
Probable Cause
Low fuel Pressure
Vacuum leak on Engine
Failed HO2S (Heated Oxegen Sensor) Bank 2

P0300
Definition
Random Cylinder Misfire Detected
Explanation
Lean Air/Fuel Ratio
Probable Cause
Ignition System misfire Condition
Fuel Injector Fault
Engine Mechanical Condition

P0306
Definition
Cylinder 6 Misfire
Explanation
Vacuum Leak on Engine
Probable Cause
Ignition System fault
Fuel Injector Failure
Engine Mechanical Condition

P1250
Definition
Fuel Level Too Low
Explanaiton
Open or Short Circuit Condition
Probable Cause
Failed Fuel Level Sensor

P0303
Definition
Cylinder 3 Misfire Condition
Explanation
Vacuum Leak on Engine
Probable Cause
Ignition System Fault
Fuel injector Fault
Engine Mechanical Condition

P0102
Definition
Mass or Volume Air Flow Circuit Low Input
Explanation
Air Duct Tubr damaged
Probable Cause
Large Vacuum Leak on Engine
Faulty MASS Sensor

P1136
Definition
Long Term Fuel Trim Add. Fuel B1 System too Lean
Explanation
Failed MAF
Probable CauseLow Fuel Pressure
Vacuum Leak on Engine
Failed HO2S (Heated Oxygen Sensor) Bank 1

Ok, So all these come up immedietly after I replace my MAF and redo all my intake piping. I also checked for vacuum leaks and any other possible thing I could find. I found that the breather hose that connects to the throttle body had came off towards the bottom of the car so I put that back on. But other than that does anybody have any idea of whats going on? The car has a tendancy to bog down at very low rpms, and it has backfired on me twice in the past two days from starting on a hill. Next step is going to be replacing the plugs and wires but apart from that anyone have any ideas?

 

After you put new plugs in and gap them right I would try to clear the codes. Drive it for a while and see what codes pop up.

 

Agreed. You can probably hold off on the wires unless you see visible damage - they're expensive and very rarely fail. Did you put a new MAF in or a used one?

 

Fuel filter, too. But that MAF code is the most suspicious. Clean the MAF to start with.

 

I put in a used MAF that I plainy stole in broad daylight from the junkyard... But the MAF I got was from a 94 Audi 100QM and I'm pretty positive it's interchangable. At least my car runs ok so I assume I'm doing something right. And i grabbed the old one and pulled it apart and checked it out. It seems pretty clean and everything. I was thinking of grabbing some carb cleaner and spraying down some of the vacuum lines, if I hear an increase in rpm's then i have a leak, if I dont, then great.

 

And btw can someone tell me what the extreme porpouse of that obnoxoius plastic hose that connects to the stock airbox then through some mechanism, then to the throttle body? Cause the hose that the mechanism blows into when you start the car cold and unhooked and making a crazy leaf blower type sound till I put it back on. But is there really a porpouse to putting the breather filter on the other end of that hose?

 

If you mean the crappy plastic hose that's about an inch in diameter, that goes down to the SAI (secondary air injection pump), then another one goes from that to the combi valve on the back of the engine (at least that's where it's located on the 1.8)

If not, then can you get a pic?

I'd say check out the MAF part numbers for those car or something. Try cleaning the MAF with the appropriate cleaner. They are EXTREMELY precise so it doesn't take much to mess them up/throw them off.

 

Correct sir. Mine is on the front of the engine but that is the one. Does the breather really serve a porpouse? And what would it have messed up if the output line was disconnected?

 

The SAI system is actually an emission control device. Also called just an "air pump" or a "smog pump," it injects air into the exhaust stream when the car first starts up to help the catalytic converter work more efficiently at startup. You can remove the system but you'll get emission codes (which can be tuned out, but commercial tunes to do so are only available on 2001s at the moment as far as B5s go... as far as I know, anyway)